The invention relates to a drill boom arrangement for positioning an elongated rock drilling apparatus to different drilling positions with respect to a boom support.
In previously known drill boom arrangement of this type it is known to swing the boom laterally by means of a first hydraulic cylinder and vertically by means of a second hydraulic cylinder. A disadvantage with such a construction is that only one of the two hydraulic cylinders is continuously loaded by the weight of the drill boom. This means that air present in the hydraulic system can cause not desired jerky movements of the drill boom.
It is an object of the invention to provide a drill boom arrangement of the above type in which both of the two hydraulic cylinders are continuously loaded by the weight of the drill boom and in which there is required less space at the boom support which is important when the booms are mounted in groups. Another object of the invention is to provide a drill boom arrangement in which each of the two hydraulic cylinders swings the boom both laterally and vertically in order to reduce the weight and volume of the hydraulic arrangement. A further object of the invention is to provide a drill boom arrangement in which two hydraulic cylinders which are pivotally coupled between the drill boom and a boom head carrying the elongated rock drilling apparatus are continuously loaded by the weight of the rock drilling apparatus. A still further object of the invention is to provide a drill boom arrangement in which the projection of the hydraulic cylinders at the boom head is reduced in order to permit the rock drilling apparatus to rotate 360.degree. about an axis which is parallel with its longitudinal axis.
The above and other purposes of the invention will become obvious from the following description and from the accompanying drawings in which one embodiment of the invention is illustrated by way of example. It should be understood that this embodiment is only illustrative of the invention and that various modifications thereof may be made within the scope of the accompanying claims following hereinafter.